Prior valves describe temperature control valves which use bimetallic or other expandable coil springs for temperature control. Among these patents are U.S. Pat. No. 5,123,593 of Rundle, which describes a manual override heat sensitive valve, U.S. Pat. No. 4,619,320 of Adnyana which describes a subsurface well safety valve and control system, U.S. Pat. No. 4,840,346 also of Adnyana which describes an apparatus for sealing a well blowout, U.S. Pat. No. 4,778,104 of Fisher, which describes a temperature responsive line valve, U.S. Pat. No. 4,848,388 of Waldbusser, which describes an emergency valve with test capabilities, U.S. Pat. No. 4,969,598 of Garris, which describes a control valve, U.S. Pat. No. 4,515,213 of Rogen, which describes a packing tool apparatus for sealing well bores, U.S. Pat. No. 5,259,554 of Ewing which describes a temperature responsive pilot operated line valve with a shape memory alloy actuator, United Kingdom Patent no. GB 2,203,791A of Michael which describes a securing device, PCT WO 92/14083 of Gordon which describes an emergency valve and PCT WO 93/07636 of Powell which describes a shape memory device.
Typical related-prior art devices having coil spring shape metal elements therein are manufactured by Resources Conservation, Inc. of Greenwich, Conn. 06830 under the tradename of SCALDSAFE.TM. and by Memry Corp. of Brookfield, Conn. under the tradenames of MEMRYSAFE.RTM. and FLOWGARD.RTM..
In summary, with respect to related temperature controlled water valves, the temperature control valves in the related prior art devices are usually continuously controlled by a bimetallic shape metal element coil spring, which expands under a predetermined temperature range when they are actuated, so that the hot water stops flowing. Also, the aforementioned patents discloses valves which can be actuated by an increase in heat so that the safety shut off feature of the valve is actuated. However, because of the temperature responsive shape metal element coil spring, the prior art patents shut off at a safe temperature which may be too low for optional comfort, such as below 110.degree. F. Therefore, one cannot use these prior art patents to achieve a hot, but safe, water temperature of 115.degree. F.
The prior art in technologies unrelated to domestic showers also includes heat responsive power elements, which include sealed cavities having an expandable waxy substance composition consisting essentially of paraffin and a metal such as copper. These power elements are used primarily in machinery thermostats, such as in metal bath preparations or for motor vehicle engines, or to control hydraulic fuel temperatures in aircraft valves.